Nassau is moving to reassess every residential and commercial property in the county for the first time since County Executive Edward Mangano froze increases in property values more than four years ago.

The new assessments are expected to take effect Jan. 1, 2018, the day after Mangano's current term ends, and three years later than originally proposed by the county executive, records show.

Fulfilling a campaign pledge, Mangano in 2010 announced he would move to a four-year assessment cycle. Effective January 2011, Mangano froze increases in property tax values, which had been updated yearly since Nassau's countywide reassessment in 2003 -- the first widespread overhaul of property values since 1938.

New values were to be in place by Jan. 1 of this year. But Mangano spokesman Brian Nevin said the reassessment program was delayed by superstorm Sandy, which damaged properties across the county.

Mangano had predicted that freezing assessment increases would help stabilize and correct values in a system that generated thousands of tax protests and an average $100 million in property tax refunds every year, which the county borrowed to pay.

But tax protests have continued to soar despite the freeze, which increases property taxes for homeowners who don't protest.

This year, the number of residential and commercial property owners challenging their values rose to an all-time high of 175,654, compared with the old record of 160,548 challenges filed in 2003 after the countywide reassessment. Of this year's total protests, nearly 154,000 were filed by single-family homeowners.

In 2011, Mangano instituted a residential settlement program, initially set up by outside appraisal firm Standard Valuation Services, to decide challenges before tax bills are issued. The program has largely eliminated residential refunds, which averaged $20 million a year for more than a decade.

Mangano also instituted a program for commercial property protests -- which historically generated $80 million a year in refunds -- that would essentially force businesses to finance their own refunds. Commercial tax attorneys have announced plans to challenge the program when it begins next year.

Asked what the freeze accomplished, Nevin said, "For the first time in decades, every residential challenge is reviewed and corrected if necessary prior to finalizing the assessment roll, thanks to reforms implemented by County Executive Mangano."

He said residents receive their correct home value before paying taxes, they no longer have to pay taxes they do not owe, and future generations will have near zero debt liability.

But the settlement program has reduced assessments every year for more than 70 percent of homeowners who grieve their values, driving up taxes for those who don't grieve.

"It is still possible for a resident to experience a double-digit increase in his or her property tax bill," the county legislature's budget review office concluded in a 2013 review of the assessment system. "Lower assessed valuations are triggering property tax rate increases. Since the county has frozen assessments, everyone, except those who successfully grieved their parcels, are paying a greater share."

In 2013, Newsday found that Nassau homeowners have seen their school tax rates jump 19.1 percent over two years largely because of lowered assessed values.

"Reassessment is a futile exercise if they're only going to freeze values while routinely granting challenges as they have done for the past four years," said Jeff Gold, a member of the former Nassau Board of Assessors, which monitored the 2003 reassessment. Gold, an attorney, lectures and has a Facebook page on how homeowners can challenge their assessments.

Gold said oversight is needed for the planned update. He noted that he and the board had found that waterfront homes initially had been undervalued during the first reassessment, conducted by national mass-appraisal firm Cole Layer Trumble.

"Without oversight this is going to be an absolute disaster," Gold said.

Nassau has included $8 million in its capital budget for reassessment, calling it a "systematic review and analysis" of the assessment system.

The Mangano administration first submitted a $4.7 million contract with Standard Valuation Services, headed by Matt Smith, to do the review. Smith was a consultant on the 2003 reassessment, did appraisals for the previous Democratic county administration and has been paid more than $2.9 million during the Mangano administration. He and his wife, Joanne, have contributed $84,000 to Mangano's campaign committee, the county's Republican committee and the Hicksville Republican committee, headed by Mangano's Chief Deputy Rob Walker, since 2010.

Smith's price was $2 million higher than that of Michael Haberman Associates, the only other firm that responded to the county's 2013 request for proposals for the professional services agreement. Haberman also was a consultant on the 2003 reassessment.

State records show that neither Haberman nor his wife has contributed to Mangano's campaign committee, the Nassau GOP or the Hicksville Republican committee since 2010.

County officials rated Smith's proposal the best because it met all requirements, but gave no further detail. Smith did not respond to a request for comment.

But the Mangano administration pulled Smith's proposed contract from the county legislature's May 11 Rules Committee agenda. Jerry Laricchiuta, president of Nassau's Civil Service Employees Association, said he asked that the contract be pulled because his members should do most of the reassessment work.

Nassau laid off nearly 60 assessment employees after Mangano imposed the freeze and Smith set up the settlement system. Laricchiuta said a labor arbitrator ruled that at least 21 of the workers were improperly terminated and owed back pay. But he said the arbitrator decided they were not eligible to get their jobs back because their work had been eliminated. If the county is starting to reassess, "it's still our work," Laricchiuta said.

Deputy County Executive Ed Ward said Nassau has issued a new request for proposals to update the 2013 plan and address union concerns. This time, bidders can choose to review one, two or all of Nassau's four classes of property: residential, condominiums and apartments, utilities, and business. He said the change should attract more vendors.

He said the county expects to submit a reassessment proposal to the legislature by June 22. Nevin said the delay should not affect the project's timeline.